1. Field of the Invention
The invention relates to a printing apparatus, and particularly relates to a three-dimensional printing apparatus.
2. Description of Related Art
With the continuous development of science and technology, various methods using the additive manufacturing technology to construct three-dimensional (3-D) models have been proposed. Generally speaking, the additive manufacturing technology converts design data of three-dimensional models constructed with computer-aided design software, for example, into a plurality of thin (pseudo-two-dimensional) cross-sectional layers that are continuously stacked.
Currently, several ways to form the thin cross-sectional layers have been developed. For example, a movable platform may be disposed in a liquid-state forming material, and an X-Y-Z coordinate system constructed according to the design data of the three-dimensional model drives a light source to move along the X-Y coordinate and irradiate the liquid-state forming material, so as to solidify the liquid-state forming material into a desired shape of the cross-sectional layer. Then, as the movable platform moves along the Z-axis, the solidified material may be formed into a three-dimensional object through solidification in layers.
However, as the current light sources for solidifying materials are mainly laser light sources, a focal length between the laser light source and the target of irradiation is required due to the limitation of the optical element required by the laser light source. Therefore, a point light is used to linearly scan back and forth along the X-Y axis in the liquid-state forming material. Such scanning manner may produce a sawtoothed structure in the surface profile when scanning an arc or curved profile, resulting in an undesirable influence on the appearance. Thus, modifying the undesirable appearance now becomes an important issue for the artisans of this field.